1. Field of the Invention
The invention relates to a centrifugal pump provided with an impeller, a pump shaft, a pump housing as well as with a motor coupled to the pump housing and the pump shaft, and where a shaft seal device circumscribes the pump shaft and is provided with a first set of sealing means arranged between the rear wall and the pump shaft and with a second set of sealing means arranged so as to prevent coolant such as cooling water from leaking between the shaft and a cooling unit mounted on the outer surface of the rear wall, and where a preloaded spring means such as a coil spring is arranged between the two sets of sealing means.
2. Background Art
For a long time, it has been desired to enhance the efficiency of the shaft seal devices arranged on centrifugal pumps at the location where the pump shaft extends through the rear wall of the pump housing so as to reduce an undesirable leakage of the pump fluid.